Caffeine health risks: Just a storm in a coffee cup?

Is it time to wake up and smell the coffee? Most of us can’t function without it in a morning but can too much coffee kill you? We ask whether we should cut down on our daily intake or drink up.

We are a nation of coffee drinkers. Every day, it is estimated we sip our way through 70million cups in Britain.

But is it good for us? Young people have been advised to avoid heavy coffee consumption by researchers who have studied its effects.

Drinking more than four cups a day can increase your risk of dying if you are under 55 but no adverse effects were found for older coffee addicts, the study’s findings suggest.

Young women who drank more than 28 cups each week were also twice as likely to die as those who avoided coffee altogether. For young men, a trend towards a higher mortality risk was found even if fewer than four cups were drunk each day, the University of South Carolina study shows.

This is not the first time coffee has been linked to chronic health conditions. Heart disease, strokes and cancer have all been previous concerns. But for every risk, a health benefit has been found, making coffee consumption a tasty debate.

The study’s co-author, Prof Conrad Earnest, of the University of Bath, said: ‘What we end up getting in these types of studies are pieces to a puzzle, which are sometimes contradictory. The first rule of epidemiology for the lay reader should be never take one study as a defining study. It is only one piece of information. Now, if a number of studies come out showing the same thing, then it is time to take notice.

‘We found that men under the age of 50 had a slightly higher risk of mortality due to cardio-vascular disease and all-cause mortality if they drank more than 28 cups of coffee per week.

‘But I am not even sure our results are something to worry about if one considers the long-standing dogma of “all things in moderation”. If you are drinking 20 cups of coffee per day that would be a concern but generally I think the benefits of coffee outweigh the negatives.’

For every study that will find something negative about coffee, ten will find something positive, added Dr Sarah Schenker, a dietician and member of the British Coffee Association’s expert task force.

‘This study goes against a lot of other research that suggests that coffee, whether it is to do with antioxidants or caffeine content, can actually be beneficial to health,’ she said.

‘You can look at coffee and caffeine in relation to lots of different disease risks and find that it is quite favourable.

‘For instance, coffee can help to reduce your risk of type 2 diabetes, Alzheimer’s and Parkinson’s disease. There is also an inverse relationship between coffee and some cancers, too, where it actually has a protective effect. That is the nature of research though. We are constantly looking to find out more about how the body works in relation to certain things that we eat and drink.’

As Dr Schenker said, coffee has been linked to preventing the onset of degenerative illnesses, helping to control Parkinson’s tremors and lowering the risk of heart disease.

Experts believe this is because of the antioxidant activity found within coffee, which is higher than in herbal tea, green tea and cocoa.

Although caffeine raises our levels of alertness and cognitive function, it can also increase our blood pressure and inhibit insulin activity.

Prof Earnest added: ‘Recent studies in rats with high blood pressure show that caffeine increases aortic stiffness and plaque formation in arteries for up to three hours after consumption. This increase in blood pressure is also present in humans for the same timeframe. Similar responses are noted during pregnancy, which always calls into question foetal blood flow.’

As a result, the Food Standards Agency advises pregnant women to limit caffeine – also found in fizzy drinks and chocolate – to 200mg, the equivalent of two cups a day.

Moderate coffee consumption is considered to be four cups of freshly brewed coffee or five cups of instant coffee a day, which equates to about 400mg of caffeine.

The British Heart Foundation says consuming these amounts does not lead to coronary heart disease, arrhythmias or affect an individual’s blood pressure.

‘One cup of coffee in the morning for someone with high blood pressure isn’t going to do you any harm. But if you already have high blood pressure and are feeling stressed, I wouldn’t advise drinking three cups in a row,’ added Dr Schenker.

‘If you have too much caffeine in your system, it will have the opposite effect. Rather than making you more able to concentrate and boosting your alertness, too much caffeine can make you irritable and restless.’